Herbicidal phosphorus pentafluoride-substituted nitriles adduct complexes

ABSTRACT

METHOD OF COMBATTING WEEDS WITH COMPOUNDS WHICH ARE ADDUCT COMPLEXES OF PHOSPHORUS PENTAFLUORIDE AND CONTAIN SUBSTITUTED NITRILES CORRESPONDING TO THE FORMULA   (R~(CH2)N~C=N$PF5)   IN WHICH N IS AN INTEGER FROM 1 TO 3, INCLUSIVE, AND R IS HYDROGEN, LOWER ALKOXY, MONPHOLINO, AND SUBSTITUTED AMINO IN WHICH THE SUBSTITUENTS ARE HYDROGEN, LOWER ALKYL, LOWER ALKENYL OR CYCLOBOXYL.

United States Patent Int. Cl. A01n 9/36 US. Cl. 7186 6 Claims ABSTRACT OF THE DISCLOSURE Method of combatting weeds with compounds which are adduct complexes of phosphorus pentafluoride and contain substituted nitriles corresponding to the formula [R-(CH CEN"PF5] in which n is an integer from 1 to 3, inclusive, and R is hydrogen, lower alkoxy, monpholino, and substituted amino in which the substituents are hydrogen, lower alkyl, lower alkenyl or cycloboxyl.

This application is a division of copending application Ser. No. 450,264, filed Apr. 20, 1965, now US. Pat. No. 3,438,983, Apr. 15, 1969.

This invention relates to certain new and novel organic compounds which may be used as herbicides. More particularly, this invention pertains to complex addition products of phosphorus pentafluoride and certain substituted nitriles as represented by the following formula:

wherein n is an integer from 1 to 3, inclusive, and R is selected from the group consisting of hydrogen, alkoxy, morpholino and. substituted amino wherein said substituents are selected from the group consisting of hydrogen, alkyl, alkenyl and cycloalkyl.

It has been found that the new and novel compounds of the present invention are particularly effective as herbicides. They are eifective in the control of grasses and broadleaf plants exhibiting both pre-emergence and postemergence activity.

The compounds of the present invention can be prepared by various methods. One such method is b contacting the appropriate nitrile under anhydrous conditions with gaseous phosphorus pentafluoride in a cooled normally inert liquid organic solvent, such as benzene, toluene and the like. The products can be obtained in very high yields and technical purity. A

Although the exact nature of the phosphorus pentafluoridenitrile adducts of the present invention have not as yet been fully determined, the evidence gathered thus far indicates them to be a type of addition product, since their formation is not accompanied by the elimination or formation of any detectable byproducts. In lieu of more substantial evidence as to the exact nature of the instant compounds any further discussion along theoretical lines of possible structure will be foregone. It should be.

Patented Jan. 26, 1971 EXAMPLE 1 Preparation of diethylaminopropionitrile-phosphorus pentafluoride complex Under anhydrous conditions, 19.0 g. (0.15 mol) of phosphorus pentafluoride gas were passed into a solution of 12.6 g. (0.1 mol) of diethylaminopropionitrile in ml. of benzene at 25-30 C. with adequate stirring. A yellow solid precipitated and was recovered by filtering. After washing with benzene and drying under anhydrous conditions a yield of 18 g. or 71% of theory was obtained M.P. 76-78 C.

Analysis.Calcd. for C H N -PF (percent): carbon, 33.2; hydrogen 5.5; phorphorus, 12.6. Found (percent): carbon, 32.9; hydrogen, 5.9, phosphorus, 12.6.

EXAMPLE 2 li-N-morpholinopropionitrile-phosphorus Preparation of pentafluoride complex In the same manner as Example 1, 19.0 g. (0.15 mol) of phosphorus pentafluoride gas were passed into a solution of 12.4 g. (0.1 mol) of fl-N-morpholinopropionitrile in 100 ml. of benzene at 2530 C. with stirring. There was obtained 9 g. of product with a melting point of 124- 128 C.

Analysis.-Calcd. for C H N O-PF (percent): Nitrogen, 11.2; phosphorus, 12.7. Found (percent): Nitrogen, 11.0; phosphorus, 11.7

EXAMPLE 3 Preparation of diethylaminobutyronitrile-phosphorus pentafluoride In the same manner as Example 1, 19.0 g. (0.15 mol) of phosphorus pentafluoride gas were passed into a solution of 14.0 g. (0.1 mol) of diethylaminobutyronitrile in 100 ml. of benzene at 2530 C. with stirring. There was obtained 14 g. of product with a melting point of 59 61 C.

Analysis.-Calcd. for C H N -PF (percent): Fluorine, 35.6; phosphorus, 12.0. Found (percent): Fluorine, 35.1; phosphorus, 11.8.

The following is a table of the complexes prepared according to the aforedescribed procedures. Compound numbers have been assigned to each member and are used in reference throughout the balance of the application.

Conipound number:

N,N-diethylarnino. 2 N,N-dimethylamino. 3 N,N-diethylamino. 2 N-methylamino.

2 Morpholino.

2 N-cyclohexylarnino. 1 Hydrogen.

2 Methoxy.

2 N,N-diallylamin0.

2 Hydrogen.

2 N,N-di-n-propylamino.

*No. 1 prepared in Example 1. No. 5 prepared in Example 2. N0. 3 prepared in Example 3.

compressed paper flats 8%X6 /2" which are 2%" deep. Enough seeds were planted to give about thirty to fifty plants each of the plant species in each flat. The flats were water after planting. The following day each flat was sprayed at the rate of 20 pounds of the candidate compound under test in 80 gallons of solution per acre. An atomizer was used to spray the solution on the soil surface. Two weeks later the degree of weed control was determined by comparing the amount of germination and growth of each weed in the treated flat with weeds in several untreated control flats. The herbicidal activity of the compounds is reported in Table II.

TABLE II.PREEMERGENCE ACTIVITY NoTn.+ =Severe injury, death or inhibited germinan. ++=Moderate injury, such as leaf malforma tion or leaf burn.

+=Slight injury, such as leaf burn.

Post-emergence herbicide test.Seeds of crab grass, pinto bean, curled dock, red oats, Indian mustard and water grass were planted in flats as used in the pre-emergence testing. The plants were allowed to emerge from the soil and develop to 3 to 6 inches in height. Thereafter, the compound under test was applied to foliage by means of an overhead spray while the fiat moves under the spray on a moving belt. A concentration of 0.5% of active compound in the spray was used at a rate of approximately 20 lbs/acre. Two weeks later the injury was rated and recorded as indicated in Table III.

TABLE III.POSI-EMERGENCE ACTIVITY The compounds of the present invention may be used as pre-emergence or post-emergence herbicides and may be applied in a variety of ways at various concentrations.

In practice the compounds are usually formulated with an inert herbicidal adjuvant, utilizing methods well-known to those skilled in the art, thereby making them suitable for application as dusts, sprays or drenches. The amount applied will depend upon the nature of the seeds or plants to be controlled and the rate of application may vary from 1 to pounds per acre. One particularly advantageous way to applying the herbicidal composition comprising the adjuvant and an effective amount of a compound of the present invention is as a narrow band along a row crop, straddling the row.

Various changes and modifications may be made without departing from the spirit and scope of the invention described herein as will be apparent to those skilled in the art to which it pertains. 'It is accordingly intended that the present invention shall only be limited by the scope of the appended claims.

What is claimed is:

1. The method of combating weeds comprising applying to the plant habitat a phytotoxic amount of a compound of the formula wherein n is an integer from 1 to 3, inclusive, and R is selected from the group consisting of methoxy, morpholino and substituted amino wherein said substituents are selected from the group consisting of hydrogen, lower alkyl having from 1 to 4 carbon atoms, inclusive, allyl and cyclohexyl.

2. The method of combating weeds comprising applying to the weed habitat a phytotoxic amount of the compound, diethylaminopropionitrile-phosphorus pentafluoride complex.

3. The method of combating weeds comprising applying to the weed habitat a phytotoxic amount of the compound, dimethylaminopropionitrile-phosphorus pentafiuoride complex.

4. The method of combating weeds comprising applying to the weed habitat a phytotoxic amount of the compound, methylaminopropionitrile-phosphorus pentafluoride complex.

5. The method of combating weeds comprising applying to the weed habitat a phytotoxic amount of the compound, fl-N-morpholinopropionitrile-phosphorus pentafluoride complex.

6. The method of combating weeds comprising applying to the weed habitat a phytotoxic amount of the compound, propionitrile-phosphorus pentafluoride complex.

References Cited UNITED STATES PATENTS 12/1966 Szabo et al. 260-566 6/1965 Mussell 7186 

